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Minutes of a Meeting on March 16 Re: HVAC Matters with Building Engineers
PRESENT
Engineers: Michael Moore, P.E. and Jack McNabb, P.E.
Board: John Filice (Chairman of the HVAC Committee), Dwight Clark,
Elizabeth VanderPutten, Roger Hirschland
Manager: Walter Krolman
HVAC Committee members Eileen Collins and Brian Larkin
Owners: Bruce Branson, Don Benedick, Leila Ryland Swain
BACKGROUND
On Jan. 24, the HVAC, chaired by John Filice, asked Michael Moore to investigate the HVAC system at the Lauren in order to provide a second opinion—second to that of Jack
McNabb. McNabb was the first engineer to study the system for the board. At the annual meeting in 2005, the membership had asked the board to commission a backup study.
Moore: “You’ve got to do something. The place is 34 years old. You’ve got issues with the condensate pans and with mold behind the walls.”
Following are items to address regarding the Lauren HVAC system:
1. Cleaver Brooks boiler.
Probably running at 55%. Designed for oil; running on natural gas. Chillers are OK. Cooling tower may be an issue, over time. Boiler should be tested for efficiency and replaced if too inefficient.
2. Corridor system.
Fundamental problem is this: terrible air distribution (25% in and out). Also, we’re exhausting heat and wasting fuel. There are heat recovery devices. (McNabb: We need to consider the physical space for that equipment. But a heat recovery device should help. Recovery of expense possible in three years.)
Moore: We need to look into hard costs. “Very, very cost effective” to get a new system.
Moore: There are two issues here: energy saving and proper distribution of air in the corridors. It would make sense to implement both aspects at the same time—circulation and energy savings.
3. Piping noise and water balancing.
Moore: McNabb is working on it and has a handle on it. “I have to defer to Jack.”
4. Condensate drain pan failures.
Several failures have caused extensive damage. Whalen units are simple. The drain pan is the condensate removal item. If you line pans as a short-term (two-year) solution, do it only if you get a Whalen expert to do it—not just any repairman—so you don’t create cold sheet metal that will soak gypsum.
[Note that lining the pans is described as only a short-term solution, not a permanent fix.]
New Whalen units do not have exactly the same “footprint” as existing units. Replacements should be done one tier at a time. If you buy in bulk, you get a better price. Get a good-size company who can work fast and efficiently.
The two-pipe system is what we have. If we go with a two-pipe system with an electrical upgrade, the advantage would be that residents in troublesome units could put on heat if it got too cold for them in summer.
A four-pipe system would require lots of drilling in the floors, but would allow each unit to heat and cool at whim.
5. Water-cooled heat pump.
They are very quiet and not objectionable. In very cold or very hot days, you can augment heat or cooling. They are extremely efficient.
6. Mitsubishi system.
This system is tremendously efficient. It shunts refrigeration back and forth. If we’re interested, we’d need Mitsubishi to come here. The big issue is
distribution of air in the unit itself. Users would have the choice of cooling or heat all year. Also, it does away with the boiler and chiller. It requires minimal maintenance and is feasible.
Moore: I think the heat pump or Mitsubishi is the way to go.
McNabb: Look at the costs. Also, look at the physical space for rooftop equipment.
The Mitsubishi unit costs about $14,000 per unit.
McNabb: The engineering fee is about 10% of equipment cost.
7. Units 1004 and 711.
The air-flow problems are attributable to initial construction dust that built up. The units are clogged. McNabb and Moore got similar results in testing output. Discussion ensued about the efficacy of cleaning the coils. Apparently residue builds up on the coils. That residue, not only impedes air flow but also insulates the coils so that air is not cooled as it passes over them. The cleaning of the coils for the unit in 711 was found to improve air flow but not significantly affecting cooling. Apparently, removing as much residue as possible made room for more air to pass among the coils, but left enough residue, or “gunk,” to adversely affect the cooling function of the coils.
Moore: Get the Whalen man in and check the squirrel-cage fan (to make sure it’s turning in the correct direction). If it’s going backward, it’s easy to correct. If it’s OK, probably clogging is the issue.
In the 04 tier, the 1” pipes have to be 1 1/2” pipes and they need to be reversed (feed and return). It is possible to install an independent unit for 1004—or a fan-coil unit in the ceiling or a split system from the roof.
Moore recommends: Take out the Whalen unit and examine it. Then install a fan-coil or split system. This would cost about $5,000 to $6,000 plus $2,000 for the removal of the Whalen unit. [As to the length of time the Lauren has before having to replace the Whalen units, it should be noted that Moore reported (Item 6 in his report): “Should an existing Whalen unit be removed from service, that unit could be taken apart and thoroughly examined. Of significant value would be to perform a metallurgical examination on the copper convective water tubing for pitting, cracking, hardening, or any other factor that could result in future tube failures and coolant leakage.” What the Lauren would get from this exercise is that it would give us some empirical evidence about how much time the condo has before having to replace the units.]
McNabb recommends a fan-coil rig using the existing chilled-water system.
Concluding Notes
Both engineers say we have to do something to replace the Whalen units. The question is when.
Moore: There may be funds available from the Department of Energy or elsewhere to help in our project.
Pepco can give us estimates on cost savings.
A water-cooled heat pump would probably be the most cost-effective route.
RESPECTFULLY SUBMITTED
Roger Hirschland
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http://www.lauren.org/lrn_business.htm